Fanfiction.net might also be a good place to look. There are many different types of fanfics on that site. However, the search might be a bit trickier as there are so many stories, but with some patience and using the right tags, you could find what you're looking for.
One good 'dom nico sub percy fanfic' could be 'The Shadows and the Seas'. In it, Nico's dominant nature is shown through his control over the shadows, while Percy, in a submissive role, has to rely on Nico's powers at times. It's an interesting take on their characters.
You can try some fanfic websites like Archive of Our Own (AO3). It has a large collection of BTS - related fanfics, including those with dom sub themes. Just use the search function and type in relevant keywords.
You can find Percy Nico fanfic on fanfiction.net. It has a large collection of stories related to various fandoms, including Percy Jackson, and you'll surely find some great Percy Nico fanfics there. Another place is Archive of Our Own (AO3). It's known for its wide range of fan - created content, and the tagging system makes it easy to search for specific types of Percy Nico fanfics.
You can start by looking on fanfiction.net. It has a large collection of fanfics related to Percy Jackson and his friends. Just search for 'Percy Thalia Nico' in the search bar and you'll get a bunch of results.
Archive of Our Own (AO3) is also a great place. It has a lot of well - written 'percy jackson and nico fanfic'. The site allows for more detailed tagging and searching, so you can find fanfics based on specific themes, ratings, or even the length of the story.
Some Tumblr blogs are dedicated to sharing and discussing 'Percy Jackson' fanfic. You can search for blogs that focus on this particular area and might be able to find some 'Percy Jackson and Nico lemon fanfic' there. But be aware that Tumblr's search can be a bit hit - or - miss, so you might need to dig a little deeper.
You can try fanfic websites like Archive of Our Own (AO3). It has a large collection of Buffy - related fanfics, and you can use the search function to look for ones with the Buffy sub Xander dom theme. Just type in relevant keywords and browse through the results.
Another option is to check out some Harry Potter - focused fan communities on social media platforms like Tumblr or Reddit. People often share and recommend fanfictions in those communities, and you may come across some good 'dom Harry sub Snape' fanfictions through their posts or discussions.
You can try fanfic websites like Fanfiction.net or Archive of Our Own. Just search for 'Dom Harry Potter sub Blaise' in their search bars and you'll likely find a variety of fanfics. Some may be more to your taste than others, so it might take a bit of browsing.
When writing this type of fanfiction, you have to be careful not to change the core of the characters too much. For Percy, his dominance could be shown through his physical and emotional protection of Annabeth. Annabeth's submissiveness can be more about her relying on Percy's instincts in certain situations. You can introduce conflict by having other characters question or misunderstand their relationship dynamic. And don't forget to add some romance and adventure to make the story engaging.